This invention relates to interfacing microfluidic devices to the macro world and more specifically to a method and means for connecting fluid transport devices such as tubing or needles and optionally intermediate devices such as filters to inlets and outlets of microfluidic devices and microfluidic valved connections.
Devices for performing chemical analysis have become miniaturized. For example, microfluidic devices have been constructed using microelectronic fabrication and micromachining techniques on planar microfluidic chips such as glass or silicon which may incorporate a series of interconnected channels or conduits to perform a variety of chemical analysis such as capillary electrophoresis and high-performance liquid chromatography.
Microfluidic chips may have networks of chambers connected by channels which may have a dimension between 0.1 microns and 500 microns, for example. Such microfluidic chips may be fabricated using photolithographic techniques similar to those used in the semi-conductor industry, and the resulting devices may be used to perform a variety of sophisticated chemical and biological analyses. Microfluidic connectors and valves may be used to connect tubing to the microfluidic chips and to introduce and/or withdraw fluids (e.g. liquids and gases) therethrough.
As reflected in the patent literature, methods of making microfluidic connectors include placing tubing directly on a microfluidic chip surface and pouring epoxy around the tubing to permanently maintain a connection between the tubing and the microfluidic chip. A commonly used connector is an “Upchurch Connector”, manufactured by Upchurch® Scientific, acquired by the IDEX Corporation of Oak Harbor, Wash. Upchurch® connectors are plastic connectors with a ring of a polymer or adhesive material, such as epoxy, that are pressed on the microfluidic chip and heated to create a permanent bond. Typically, it is necessary to glue the Upchurch® connectors to the wafers or microfluidic chips with a special epoxy.
However, adhesive bonding may be difficult and may be unsuitable for many chemical analysis applications since solvents in a sample solution may attack the adhesive which may clog the microfluidic channels. Degradation of the adhesive may also cause the connector to leak or even detach from the microfluidic chip. Additionally, the adhesive may contaminate the sample delivered to an analytical device. Furthermore, adhesive bonding results in a permanent attachment of the tubing to the microfluidic device which makes it difficult to change components such as microfluidic devices or tubing. Once the permanent connector fails, the microfluidic device may be useless. Thus assembly, repair, and maintenance of such devices may be costly and labor and time intensive.
To avoid problems associated with adhesive bonding, other techniques have been employed, such as press fitting the tubing into a port on a microfluidic device or microfluidic chip. For example, in “A rapid, reliable, and automatable lab-on-a-chip interface”, by Kortmann H, Blank L M, Schmid A, Lab on a chip, 2009 May 9(10):1455-60, a new type of press-fit connector was introduced that incorporate springs to produce the mounting force with leak-free operation. In this approach, each connector is pressed independently against a back plate to ensure proper sealing of multiple connectors. The press-fit connectors have some advantages over the Upchurch® connectors, such as reliability, reusability and fast assembly. However, some drawbacks may be (i) high cost, (ii) high complexity as each connector may require a large number of parts, and (iii) the platform and the connectors may be required to be mounted on a fixed geometry with limited flexibility. Additionally, connections made by pressing the tubing onto a microfluidic chip may create stress loads on the microfluidic chip which may cause fractures of the channels and/or microfluidic chip.
More recently, tubes have been connected with magnetic connectors. For example, in U.S. Patent Publication 2008/0143098, invented by Zimmermann et al., entitled “Magnetic Fluid Coupling Assemblies and Methods”, an apparatus for magnetically connecting tubing is disclosed. A pair of magnets are configured to attract one another wherein both magnets have a sole tube extending there from. Each magnet has a flow through orifice configured and disposed to be in flow communication upon connecting the two magnets with one another. However, Zimmermann et al. fail to provide an apparatus for connecting microfluidic transport devices to a microfluidic chip and adjustable magnetic valve connections.
Valved connections for microfluidic devices are also disclosed in the patent literature. For example, in U.S. Pat. No. 6,910,503, invented by Schick et al., entitled “Methods and Apparatus for Micro-Fluidic Analytical Chemistry”, an apparatus for connecting tubing, in a microfluidic device, with a valve disposed in the connector is disclosed. The valve disclosed in Schick et al. comprises at least two parts with at least one through orifice in each part. In a first connecting orientation between the at least two parts, at least one through orifice in one of the parts is in flow communication with a through orifice in another part. In a second orientation between the at least two parts, flow communication between the through orifices of the two parts is altered. However, Schick et al. fail to provide a valve configured to connect tubing to a microfluidic chip and a changeable or quick release valve.
What is needed are improved microfluidic connectors and valves which overcome some of the shortcomings, disadvantages, and limitations of the connectors and valves disclosed in the patent literature.